In the semiconductor production industry, various processing steps are used to fabricate integrated circuits on a wafer. Chemical vapor deposition (CVD) process, plasma enhanced chemical vapor deposition (PECVD) method, and atmospheric pressure chemical vapor deposition (APCVD) method are well-known methods for depositing and forming layers on the underlying substrate. Silicon such as silicon nitride, silicon oxide, silicon dioxide, silicon carbide, and/or other silicon compounds are widely used in semiconductor technologies for electronic devices, such as microwave frequency integrated circuits, light-emitting diodes, laser diodes, solar cells, high-power and high-frequency electronics, and opto-electronic devices.
In a typical CVD process, the substrate is exposed to one or more volatile precursors, which react and/or decompose on the substrate surface to produce the desired deposit. Frequently, volatile by-products are also produced. For example, during silicon nitride LPCVD process, using as precursors, dichlorosilane (SiH2Cl) may be reacted with ammonia (NH3) to produce silicon nitride. The chemical reaction can be described as follows:3SiH2Cl+4NH3→Si3N4+6HCl+6H2 
By-products, for example, ammonium chloride (NH4Cl) and hydrogen chloride (HCl), may be produced in the CVD process. Ammonium chloride (NH4Cl) may leave the process furnace in vapor form but readily condense to fine powder that will accumulate in any cold surface of the vacuum system such as valve, vacuum pump, and vacuum pump exhaust line. As the build-up of by-products increase within the cold trap, system presses FIG. 4 increasingly hard to control. Frequent cleaning and/or replacing of lines, valves, and vacuum pumps may increase cost of maintenance.